1. Field of the Invention
The present invention relates to a tremolo block device for a guitar, and more particularly to a tremolo block device installed to a body of a guitar to adjust tension of strings for trill.
2. Description of the Related Art
Generally, a guitar, particularly an electric guitar, has a head 1, a neck 2 and a body 3, as shown in FIG. 1.
On the neck 2, installed are strings 4, both ends of which are respectively fixed to the head 1 and the body 3. At this time, one end of the strings 4 are fixed with pegs 1a and poles 1b mounted to the head 1. The peg 1a is rotated to adjust tension of the string 4 for tuning. The other ends of the strings 4 are fixed to a tremolo block device 5 installed to the body 3, and the tremolo block device 5 includes a bridge plate 5a, a saddle 5b and an arm 5c, which are exposed outside the body 3, and various parts installed inside the body 3 to elastically support the bridge plate 5a to be suspended in midair.
Detailed configuration of such a conventional tremolo block device is well disclosed in xe2x80x98Tail fixing device for an electric guitarxe2x80x99 (Korean Utility Model Application No. 20-2001-0037102), xe2x80x98Trilling device for a string instrument having a tuning state maintaining functionxe2x80x99 (Korean Utility Model Application No. 20-2000-0013134) and xe2x80x98Guitar tremolo block devicexe2x80x99 (Korean Patent Application No. 10-1994-0011344), and not described in detail here.
To briefly describe the configuration to help understanding, the conventional tremolo block device is configured that a front of the bridge plate 5a is combined to and supported by the body 5 by means of a pair of fixing posts 5d, and a rear of the bridge plate 5a is unstably supported in midair while tension of the strings 4 is in balance with elastic force of springs (not shown) mounted inside the body 3. If vibrating the rear of the bridge plate 5a vertically by vibrating the arm 5c during playing the guitar, the tension of the string 4 is quickly changed, so giving a trilling effect.
However, in such a conventional tremolo block device, a side of the bridge plate 5a is generally fixed only through a pair of fixing posts 5d to the body 3 made of weak material such as woods. When playing the arming to obtain the trilling effect, stress is concentrated on the fixing posts 5d. Thus, if using the guitar for a long time or playing a serious arming, a portion combined with the fixing posts 5d can be concentrated with stress and broken.
On the other hand, to change overall tension of the strings 4, a height of the rear of the bridge plate 5a should be changed for setting. If changing the rear height of the bridge plate 5a, a front height of the saddle 5b supporting the strings 4 is also changed. It may give an effect of drawing or releasing the strings 4, so tension of the strings 4 are changed. If the strings 4 are set with changed tension, a playing range and a trilling range are also changed. This is a reason that players sometimes change the rear height of the bridge plate 5a. To change the rear height of the bridge plate 5a as above, in a conventional case, a user should open a cover (not shown) formed at the back of the body 3 by using such as a screwdriver and then rotates a screw (not shown) which changes tension of a spring connected to the bridge plate 5a. Thus, such a work is very complicate and inconvenient.
In addition, as indicated in xe2x80x98Trilling device for a string instrument having a tuning state maintaining functionxe2x80x99 (Korean Utility Model Application No. 20-2000-0013134), the conventional tremolo block device has so many parts and complicated configuration. This causes difficulty in manufacturing and assembling and results in increase of costs.
The present invention is designed to solve such problems of the prior art, and an object of the present invention to provide a guitar tremolo block device in which a bridge plate is stably mounted, so preventing breakage of a body due to stress concentration even by serious arming or long time use.
Another object of the present invention is to provide a guitar tremolo block device configured that a rear height of the bridge plate can be easily adjusted from outside to change tension of strings.
Still another object of the present invention is to provide a guitar tremolo block device having the small number of parts and simple configuration, easy to manufacture and assemble, and capable of being made at low costs.
In order to accomplish the above objects, the present invention provides a tremolo block device installed to a body of a guitar so as to trill strings by adjusting tension of the strings, which includes an upper support combined to a lower surface of a bridge plate having a plurality of saddles, a lower support hinged with the upper support through a hinge axis, a worm installed through the lower support so as not to be separated from the lower support, a worm gear engaged with the worm and inserted into the hinge axis, and a spring inserted into the hinge to rotate together with the hinge and elastically supporting a lower portion of the upper support.
At this time, the hinge axis is installed through a pair of upper hinge protrusions protruded forward at both sides of the upper support and a pair of lower hinge protrusions protruded upward and spaced apart at the center of the lower support at the same time, and a bearing is inserted at a portion of the upper hinge protrusions where the hinge axis passes through.
In addition, a bushing is fit with the lower support at a position where the worm passes through, and at least one flat portion is formed respectively at a contact surface of the worm gear and the hinge axis in order to prevent slipping to a rotating direction.
In addition, the worm gear is positioned between the lower hinge protrusions, the worm is positioned between the worm gear and the upper support, and a dented worm guide groove is formed at one side of the upper support so as to ensure a space where the worm is installed.
On the other hand in the present invention, when the upper support rotates to the lower support on the center of the hinge axis, an upper end of the worm keeps a space with the upper support, and a ring groove is formed along a lower circumference of the worm positioned below the lower support and a snap ring is inserted to the ring groove in order to prevent the worm from releasing upward, and a screwed upper portion of the worm is thickly formed and supported on an upper surface of the upper support in order to prevent the worm from releasing downward.
In the present invention, there is provided a pair of springs, and each of springs is mounted between the upper hinge protrusions and between the lower hinge protrusions, and a spring support projection is formed at facing inner sides of the upper hinge protrusions in order to support the springs.
In addition, the springs are wound around an outer circumference of a spring fixing member which is combined to the hinge axis and rotates together with the hinge axis, and one end of the spring is inserted and fixed into a fixing groove formed at one end of the spring fixing member, and at least one flat portion is formed respectively at a contact surface of the spring fixing member and the hinge axis in order to prevent slipping to a rotating direction.